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Creep of a cast cobalt-based alloy in 3-points flexion and dependence on the applied load

Lionel Aranda, Thierry Schweitzer, Patrice Berthod, Elodie Conrath

A cobalt-based alloy Co-25Cr-0.25C was elaborated by casting. Its microstructure was composed of a dendritic matrix and of interdendritic chromium carbides. Three parallelepiped samples were tested at 1200°C in three-points flexion under a constant load, masses leading to 10, 15 or 20 MPa as maximal stress in the middle of the sample bottom. The two first phases of creep, primary and secondary, were characterized and their dependence on the applied load studied. Laws of dependence of the deformation rate in secondary stage of creep upon the resulting maximal stress similar to what is known for tensile creep, were tried to represent this dependence. In the present case the relationship which is the most suitable is the one which corresponds to the rather low stresses.